Method for interference control in radio resource and device therefor

ABSTRACT

According to one embodiment of the present invention, a method for interference control in a radio resource having a plurality of bands and a plurality of frames comprises the steps of: allocating a dedicated data channel for a specific terminal and a common data channel for a plurality of terminals; and transmitting, to a neighboring base station, information related to the allocated dedicated data channel and common data channel, wherein the dedicated data channel can be allocated when data, to be transmitted to the specific terminal standing by in a transmission buffer, is larger than a predetermined amount.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore particularly, to a method of controlling interference in a radioresource and an apparatus therefor.

BACKGROUND ART

Recently, various devices requiring machine-to-machine (M2M)communication and high data transfer rate, such as smartphones or tabletpersonal computers (PCs), have appeared and come into widespread use.This has rapidly increased the quantity of data which needs to beprocessed in a cellular network. In order to satisfy such rapidlyincreasing data throughput, recently, carrier aggregation (CA)technology which efficiently uses more frequency bands, cognitive ratiotechnology, multiple antenna (MIMO) technology for increasing datacapacity in a restricted frequency, multiple-base-station cooperativetechnology, etc. have been highlighted. In addition, communicationenvironments have evolved such that the density of accessible nodes isincreased in the vicinity of a user equipment (UE). Here, the nodeincludes one or more antennas and refers to a fixed point capable oftransmitting/receiving radio frequency (RF) signals to/from the userequipment (UE). A communication system including high-density nodes mayprovide a communication service of higher performance to the UE bycooperation between nodes.

A multi-node coordinated communication scheme in which a plurality ofnodes communicates with a user equipment (UE) using the sametime-frequency resources has much higher data throughput than legacycommunication scheme in which each node operates as an independent basestation (BS) to communicate with the UE without cooperation.

A multi-node system performs coordinated communication using a pluralityof nodes, each of which operates as a base station or an access point,an antenna, an antenna group, a remote radio head (RRH), and a remoteradio unit (RRU). Unlike the conventional centralized antenna system inwhich antennas are concentrated at a base station (BS), nodes are spacedapart from each other by a predetermined distance or more in themulti-node system. The nodes can be managed by one or more base stationsor base station controllers which control operations of the nodes orschedule data transmitted/received through the nodes. Each node isconnected to a base station or a base station controller which managesthe node through a cable or a dedicated line.

The multi-node system can be considered as a kind of Multiple InputMultiple Output (MIMO) system since dispersed nodes can communicate witha single UE or multiple UEs by simultaneously transmitting/receivingdifferent data streams. However, since the multi-node system transmitssignals using the dispersed nodes, a transmission area covered by eachantenna is reduced compared to antennas included in the conventionalcentralized antenna system. Accordingly, transmit power required foreach antenna to transmit a signal in the multi-node system can bereduced compared to the conventional centralized antenna system usingMIMO. In addition, a transmission distance between an antenna and a UEis reduced to decrease in pathloss and enable rapid data transmission inthe multi-node system. This can improve transmission capacity and powerefficiency of a cellular system and meet communication performancehaving relatively uniform quality regardless of UE locations in a cell.Further, the multi-node system reduces signal loss generated duringtransmission since base station(s) or base station controller(s)connected to a plurality of nodes transmit/receive data in cooperationwith each other. When nodes spaced apart by over a predetermineddistance perform coordinated communication with a UE, correlation andinterference between antennas are reduced. Therefore, a high signal tointerference-plus-noise ratio (SINR) can be obtained according to themulti-node coordinated communication scheme.

Owing to the above-mentioned advantages of the multi-node system, themulti-node system is used with or replaces the conventional centralizedantenna system to become a new foundation of cellular communication inorder to reduce base station cost and backhaul network maintenance costwhile extending service coverage and improving channel capacity and SINRin next-generation mobile communication systems.

DISCLOSURE OF THE INVENTION Technical Task

An object of the present invention is to provide a method of controllinginterference in a radio resource in a wireless communication system.

Technical tasks obtainable from the present invention are non-limitedthe above-mentioned technical task. And, other unmentioned technicaltasks can be clearly understood from the following description by thosehaving ordinary skill in the technical field to which the presentinvention pertains.

Technical Solution

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, accordingto one embodiment, a method of controlling interference in a radioresource including a plurality of bands and a plurality of frames,includes the steps of allocating a dedicated data channel for a specificterminal and a common data channel for a plurality of terminals, andforwarding information on the allocated dedicated data channel and thecommon data channel to a neighboring base station. In this case, thededicated data channel may be allocated when an amount of data to betransmitted to the specific terminal, which is waiting in a transmissionbuffer, is greater than a predetermined amount.

Additionally or alternately, the information on the dedicated datachannel may include the number of the dedicated data channel, the numberof subchannels included in each dedicated data channel, and a resourceposition of each dedicated data subchannel.

Additionally or alternately, the information on the dedicated datachannel may include the number of subchannels included in a feedbackchannel or a grant channel linked with each dedicated data channel and aresource position of each dedicated feedback subchannel.

Additionally or alternately, the number of HARQ (hybrid automaticrequest transmission) processes of the dedicated data channel may bedetermined according to a time interval between the dedicated datachannel and the feedback channel or the grant channel linked with thededicated data channel.

Additionally or alternately, a transmission interval of the dedicateddata channel may be determined according to a time interval between thededicated data channel and the feedback channel or the grant channellinked with the dedicated data channel.

Additionally or alternately, a plurality of feedback channels or grantchannels associated with a plurality of dedicated data channels may bemultiplexed and allocated to a single subchannel.

Additionally or alternately, the method may include forwarding, to theneighboring base station, information on an use priority of a pluralityof sub-regions contained in the dedicated data channel. In this case,the dedicated data channel may be allocated according to the usepriority.

Additionally or alternately, the method may include the step ofreceiving information on a dedicated data channel and a common datachannel allocated for terminals of the neighboring base station from theneighboring base station.

Additionally or alternately, the dedicated data channel for the specificterminal and the common data channel for the plurality of the terminalsmay be allocated based on information on a dedicated data channel and acommon data channel allocated for terminals of the neighboring basestation received from the neighboring base station.

To further achieve these and other advantages and in accordance with thepurpose of the present invention, according to a different embodiment, abase station configured to control interference in a radio resourceincluding a plurality of bands and a plurality of frames includes an RF(radio frequency) unit, and a processor configured to control the RFunit, the processor configured to allocate a dedicated data channel fora specific terminal and a common data channel for a plurality ofterminals, the processor configured to forward information on theallocated dedicated data channel and the common data channel to aneighboring base station. In this case, the dedicated data channel maybe allocated when an amount of data to be transmitted to the specificterminal, which is waiting in a transmission buffer, is greater than apredetermined amount.

Additionally or alternately, the information on the dedicated datachannel may include the number of the dedicated data channel, the numberof subchannels included in each dedicated data channel, and a resourceposition of each dedicated data subchannel.

Additionally or alternately, the information on the dedicated datachannel may include the number of subchannels included in a feedbackchannel or a grant channel linked with each dedicated data channel and aresource position of each dedicated feedback subchannel.

Additionally or alternately, the number of HARQ (hybrid automaticrequest transmission) processes of the dedicated data channel may bedetermined according to a time interval between the dedicated datachannel and the feedback channel or the grant channel linked with thededicated data channel.

Additionally or alternately, a transmission interval of the dedicateddata channel may be determined according to a time interval between thededicated data channel and the feedback channel or a grant channelassociated with the dedicated data channel.

Additionally or alternately, a plurality of feedback channels or grantchannels associated with a plurality of dedicated data channels may bemultiplexed and allocated to a single subchannel.

Additionally or alternately, the processor may be configured to forwardinformation on an use priority of a plurality of sub-regions containedin the dedicated data channel to the neighboring base station and thededicated data channel can be allocated according to the use priority.

Additionally or alternately, the processor may be configured to receiveinformation on a dedicated data channel and a common data channelallocated for terminals of the neighboring base station from theneighboring base station.

Additionally or alternately, the dedicated data channel allocated forthe specific terminal and the common data channel allocated for aplurality of the terminals may be allocated based on information on adedicated data channel and a common data channel allocated for terminalsof the neighboring base station received from the neighboring basestation.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

Advantageous Effects

According to one embodiment of the present invention, it is able to moreefficiently perform wireless communication via interference control.

Effects obtainable from the present invention may be non-limited by theabove mentioned effect. And, other unmentioned effects can be clearlyunderstood from the following description by those having ordinary skillin the technical field to which the present invention pertains.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a diagram for an example of a radio frame structure used in awireless communication system;

FIG. 2 is a diagram for an example of a downlink (DL)/uplink (UL) slotstructure in a wireless communication system;

FIG. 3 is a diagram for an example of a downlink (DL) subframe structureused in 3GPP LTE/LTE-A system;

FIG. 4 is a diagram for an example of an uplink (UL) subframe structureused in 3GPP LTE/LTE-A system;

FIG. 5 is a diagram for subchannels allocated in a radio resourceaccording to one embodiment of the present invention;

FIG. 6 is a diagram for data channels and feedback channels allocated ina radio resource according to one embodiment of the present invention;

FIG. 7 is a diagram for data channels and feedback channels allocated ina radio resource according to one embodiment of the present invention;

FIG. 8 is a diagram for data channels and feedback channels allocated ina radio resource according to one embodiment of the present invention;

FIG. 9 is a diagram for data channels and regions to which feedbackchannels connected with the data channels are capable of being allocatedin a radio resource according to one embodiment of the presentinvention;

FIG. 10 is a diagram for a plurality of data channels and multiplexedfeedback channels connected with a plurality of the data channelsallocated in a radio resource according to one embodiment of the presentinvention;

FIG. 11 is a diagram for data channels and feedback channels allocatedin a radio resource according to one embodiment of the presentinvention;

FIG. 12 is a diagram for data channels and feedback channels allocatedin a radio resource according to one embodiment of the presentinvention;

FIG. 13 is a diagram for grant channels and uplink data channelsaccording to the grant channels allocated in a radio resource accordingto one embodiment of the present invention;

FIG. 14 is a diagram for grant channels and regions to which uplink datachannels connected with the grant channels are capable of beingallocated in a radio resource according to one embodiment of the presentinvention;

FIG. 15 is a diagram for multiplexed grant channels and uplink datachannels according to the grant channels allocated in a radio resourceaccording to one embodiment of the present invention;

FIG. 16 is a diagram for grant channels and uplink data channelsaccording to the grant channels allocated in a radio resource accordingto one embodiment of the present invention;

FIG. 17 is a diagram for uplink/downlink dedicated data channels andcommon data channels allocated in a radio resource according to oneembodiment of the present invention;

FIG. 18 is a flowchart for an operation according to one embodiment ofthe present invention;

FIG. 19 is a block diagram of devices for implementing embodiment(s) ofthe present invention.

BEST MODE Mode for Invention

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. The accompanying drawings illustrate exemplary embodiments ofthe present invention and provide a more detailed description of thepresent invention. However, the scope of the present invention shouldnot be limited thereto.

In some cases, to prevent the concept of the present invention frombeing ambiguous, structures and apparatuses of the known art will beomitted, or will be shown in the form of a block diagram based on mainfunctions of each structure and apparatus. Also, wherever possible, thesame reference numbers will be used throughout the drawings and thespecification to refer to the same or like parts.

In the present invention, a user equipment (UE) is fixed or mobile. TheUE is a device that transmits and receives user data and/or controlinformation by communicating with a base station (BS). The term ‘UE’ maybe replaced with ‘terminal equipment’, ‘Mobile Station (MS)’, ‘MobileTerminal (MT)’, ‘User Terminal (UT)’, ‘Subscriber Station (SS)’,‘wireless device’, ‘Personal Digital Assistant (PDA)’, ‘wireless modem’,‘handheld device’, etc. A BS is typically a fixed station thatcommunicates with a UE and/or another BS. The BS exchanges data andcontrol information with a UE and another BS. The term ‘BS’ may bereplaced with ‘Advanced Base Station (ABS)’, ‘Node B’, ‘evolved-Node B(eNB)’, ‘Base Transceiver System (BTS)’, ‘Access Point (AP)’,‘Processing Server (PS)’, etc. In the following description, BS iscommonly called eNB.

In the present invention, a node refers to a fixed point capable oftransmitting/receiving a radio signal to/from a UE by communication withthe UE. Various eNBs can be used as nodes. For example, a node can be aBS, NB, eNB, pico-cell eNB (PeNB), home eNB (HeNB), relay, repeater,etc. Furthermore, a node may not be an eNB. For example, a node can be aradio remote head (RRH) or a radio remote unit (RRU). The RRH and RRUhave power levels lower than that of the eNB. Since the RRH or RRU(referred to as RRH/RRU hereinafter) is connected to an eNB through adedicated line such as an optical cable in general, cooperativecommunication according to RRH/RRU and eNB can be smoothly performedcompared to cooperative communication according to eNBs connectedthrough a wireless link. At least one antenna is installed per node. Anantenna may refer to an antenna port, a virtual antenna or an antennagroup. A node may also be called a point. Unlink a conventionalcentralized antenna system (CAS) (i.e. single node system) in whichantennas are concentrated in an eNB and controlled an eNB controller,plural nodes are spaced apart at a predetermined distance or longer in amulti-node system. The plural nodes can be managed by one or more eNBsor eNB controllers that control operations of the nodes or schedule datato be transmitted/received through the nodes. Each node may be connectedto an eNB or eNB controller managing the corresponding node via a cableor a dedicated line. In the multi-node system, the same cell identity(ID) or different cell IDs may be used for signal transmission/receptionthrough plural nodes. When plural nodes have the same cell ID, each ofthe plural nodes operates as an antenna group of a cell. If nodes havedifferent cell IDs in the multi-node system, the multi-node system canbe regarded as a multi-cell (e.g., macro-cell/femto-cell/pico-cell)system. When multiple cells respectively configured by plural nodes areoverlaid according to coverage, a network configured by multiple cellsis called a multi-tier network. The cell ID of the RRH/RRU may beidentical to or different from the cell ID of an eNB. When the RRH/RRUand eNB use different cell IDs, both the RRH/RRU and eNB operate asindependent eNBs.

In a multi-node system according to the present invention, which will bedescribed below, one or more eNBs or eNB controllers connected to pluralnodes can control the plural nodes such that signals are simultaneouslytransmitted to or received from a UE through some or all nodes. Whilethere is a difference between multi-node systems according to the natureof each node and implementation form of each node, multi-node systemsare discriminated from single node systems (e.g. CAS, conventional MIMOsystems, conventional relay systems, conventional repeater systems,etc.) since a plurality of nodes provides communication services to a UEin a predetermined time-frequency resource. Accordingly, embodiments ofthe present invention with respect to a method of performing coordinateddata transmission using some or all nodes can be applied to varioustypes of multi-node systems. For example, a node refers to an antennagroup spaced apart from another node by a predetermined distance ormore, in general. However, embodiments of the present invention, whichwill be described below, can even be applied to a case in which a noderefers to an arbitrary antenna group irrespective of node interval. Inthe case of an eNB including an X-pole (cross polarized) antenna, forexample, the embodiments of the preset invention are applicable on theassumption that the eNB controls a node composed of an H-pole antennaand a V-pole antenna.

A communication scheme through which signals are transmitted/receivedvia plural transmit (Tx)/receive (Rx) nodes, signals aretransmitted/received via at least one node selected from plural Tx/Rxnodes, or a node transmitting a downlink signal is discriminated from anode transmitting an uplink signal is called multi-eNB MIMO or CoMP(Coordinated Multi-Point Tx/Rx). Coordinated transmission schemes fromamong CoMP communication schemes can be categorized into JP (JointProcessing) and scheduling coordination. The former may be divided intoJT (Joint Transmission)/JR (Joint Reception) and DPS (Dynamic PointSelection) and the latter may be divided into CS (CoordinatedScheduling) and CB (Coordinated Beamforming). DPS may be called DCS(Dynamic Cell Selection). When JP is performed, more variouscommunication environments can be generated, compared to other CoMPschemes. JT refers to a communication scheme by which plural nodestransmit the same stream to a UE and JR refers to a communication schemeby which plural nodes receive the same stream from the UE. The UE/eNBcombine signals received from the plural nodes to restore the stream. Inthe case of JT/JR, signal transmission reliability can be improvedaccording to transmit diversity since the same stream is transmittedfrom/to plural nodes. DPS refers to a communication scheme by which asignal is transmitted/received through a node selected from plural nodesaccording to a specific rule. In the case of DPS, signal transmissionreliability can be improved because a node having a good channel statebetween the node and a UE is selected as a communication node.

In the present invention, a cell refers to a specific geographical areain which one or more nodes provide communication services. Accordingly,communication with a specific cell may mean communication with an eNB ora node providing communication services to the specific cell. Adownlink/uplink signal of a specific cell refers to a downlink/uplinksignal from/to an eNB or a node providing communication services to thespecific cell. A cell providing uplink/downlink communication servicesto a UE is called a serving cell. Furthermore, channel status/quality ofa specific cell refers to channel status/quality of a channel or acommunication link generated between an eNB or a node providingcommunication services to the specific cell and a UE. In 3GPP LTE-Asystems, a UE can measure downlink channel state from a specific nodeusing one or more CSI-RSs (Channel State Information Reference Signals)transmitted through antenna port(s) of the specific node on a CSI-RSresource allocated to the specific node. In general, neighboring nodestransmit CSI-RS resources on orthogonal CSI-RS resources. When CSI-RSresources are orthogonal, this means that the CSI-RS resources havedifferent subframe configurations and/or CSI-RS sequences which specifysubframes to which CSI-RSs are allocated according to CSI-RS resourceconfigurations, subframe offsets and transmission periods, etc. whichspecify symbols and subcarriers carrying the CSI RSs.

In the present invention, PDCCH (Physical Downlink ControlChannel)/PCFICH (Physical Control Format Indicator Channel)/PHICH(Physical Hybrid automatic repeat request Indicator Channel)/PDSCH(Physical Downlink Shared Channel) refer to a set of time-frequencyresources or resource elements respectively carrying DCI (DownlinkControl Information)/CFI (Control Format Indicator)/downlink ACK/NACK(Acknowledgement/Negative ACK)/downlink data. In addition, PUCCH(Physical Uplink Control Channel)/PUSCH (Physical Uplink SharedChannel)/PRACH (Physical Random Access Channel) refer to sets oftime-frequency resources or resource elements respectively carrying UCI(Uplink Control Information)/uplink data/random access signals. In thepresent invention, a time-frequency resource or a resource element (RE),which is allocated to or belongs toPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH, is referred to as aPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH RE orPDCCH/PCFICH/PHICH/PDSCH/PUCCH/PUSCH/PRACH resource. In the followingdescription, transmission of PUCCH/PUSCH/PRACH by a UE is equivalent totransmission of uplink control information/uplink data/random accesssignal through or on PUCCH/PUSCH/PRACH. Furthermore, transmission ofPDCCH/PCFICH/PHICH/PDSCH by an eNB is equivalent to transmission ofdownlink data/control information through or onPDCCH/PCFICH/PHICH/PDSCH.

FIGS. 1A and 1B illustrate an exemplary radio frame structure used in awireless communication system. FIG. 1A illustrates a frame structure forfrequency division duplex (FDD) used in 3GPP LTE/LTE-A and FIG. 1Billustrates a frame structure for time division duplex (TDD) used in3GPP LTE/LTE-A.

Referring to FIG. 1A, a radio frame used in 3GPP LTE/LTE-A has a lengthof 10 ms (307200 Ts) and includes 10 subframes in equal size. The 10subframes in the radio frame may be numbered. Here, Ts denotes samplingtime and is represented as Ts=1/(2048*15 kHz). Each subframe has alength of 1 ms and includes two slots. 20 slots in the radio frame canbe sequentially numbered from 0 to 19. Each slot has a length of 0.5 ms.A time for transmitting a subframe is defined as a transmission timeinterval (TTI). Time resources can be discriminated by a radio framenumber (or radio frame index), subframe number (or subframe index) and aslot number (or slot index).

The radio frame can be configured differently according to duplex mode.Downlink transmission is discriminated from uplink transmission byfrequency in FDD mode, and thus the radio frame includes only one of adownlink subframe and an uplink subframe in a specific frequency band.In TDD mode, downlink transmission is discriminated from uplinktransmission by time, and thus the radio frame includes both a downlinksubframe and an uplink subframe in a specific frequency band.

Table 1 shows DL-UL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink- to-Uplink Switch- DL-UL point Subframe numberconfiguration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  D S U U UD D D D D 4 10 ms  D S U U D D D D D D 5 10 ms  D S U D D D D D D D 6 5ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes threefields of DwPTS (Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS(Uplink Pilot TimeSlot). DwPTS is a period reserved for downlinktransmission and UpPTS is a period reserved for uplink transmission.Table 2 shows special subframe configuration.

TABLE 2 Normal cyclic prefix in downlink Extended cyclic prefix indownlink UpPTS UpPTS Special Normal cyclic Extended Normal Extendedsubframe prefix in cyclic prefix cyclic prefix cyclic prefixconfiguration DwPTS uplink in uplink DwPTS in uplink in uplink 0  6592 ·T_(s) 2192 · T_(s) 2560 · T_(s)  7680 · T_(s) 2192 · T_(s) 2560 · T_(s)1 19760 · T_(s) 20480 · T_(s) 2 21952 · T_(s) 23040 · T_(s) 3 24144 ·T_(s) 25600 · T_(s) 4 26336 · T_(s)  7680 · T_(s) 4384 · T_(s) 5120 ·T_(s) 5  6592 · T_(s) 4384 · T_(s) 5120 · T_(s) 20480 · T_(s) 6 19760 ·T_(s) 23040 · T_(s) 7 21952 · T_(s) 12800 · T_(s) 8 24144 · T_(s) — — —9 13168 · T_(s) — — —

FIG. 2 illustrates an exemplary downlink/uplink slot structure in awireless communication system. Particularly, FIG. 2 illustrates aresource grid structure in 3GPP LTE/LTE-A. A resource grid is presentper antenna port.

Referring to FIG. 2, a slot includes a plurality of OFDM (OrthogonalFrequency Division Multiplexing) symbols in the time domain and aplurality of resource blocks (RBs) in the frequency domain. An OFDMsymbol may refer to a symbol period. A signal transmitted in each slotmay be represented by a resource grid composed of N_(RB) ^(DL/UL)*N_(sc)^(RB) subcarriers and N_(symb) ^(DL/UL) OFDM symbols. Here, N_(RB) ^(DL)denotes the number of RBs in a downlink slot and N_(RB) ^(UL) denotesthe number of RBs in an uplink slot. N_(RB) ^(DL) and N_(RB) ^(UL)respectively depend on a DL transmission bandwidth and a UL transmissionbandwidth. N_(symb) ^(DL) denotes the number of OFDM symbols in thedownlink slot and N_(symb) ^(UL) denotes the number of OFDM symbols inthe uplink slot. In addition, N_(sc) ^(RB) denotes the number ofsubcarriers constructing one RB.

An OFDM symbol may be called an SC-FDM (Single Carrier FrequencyDivision Multiplexing) symbol according to multiple access scheme. Thenumber of OFDM symbols included in a slot may depend on a channelbandwidth and the length of a cyclic prefix (CP). For example, a slotincludes 7 OFDM symbols in the case of normal CP and 6 OFDM symbols inthe case of extended CP. While FIG. 2 illustrates a subframe in which aslot includes 7 OFDM symbols for convenience, embodiments of the presentinvention can be equally applied to subframes having different numbersof OFDM symbols. Referring to FIG. 2, each OFDM symbol includes N_(RB)^(DL/UL)*N_(sc) ^(RB) subcarriers in the frequency domain. Subcarriertypes can be classified into a data subcarrier for data transmission, areference signal subcarrier for reference signal transmission, and nullsubcarriers for a guard band and a direct current (DC) component. Thenull subcarrier for a DC component is a subcarrier remaining unused andis mapped to a carrier frequency (f0) during OFDM signal generation orfrequency up-conversion. The carrier frequency is also called a centerfrequency.

An RB is defined by N_(symb) ^(DL/UL) (e.g., 7) consecutive OFDM symbolsin the time domain and N_(sc) ^(RB) (e.g., 12) consecutive subcarriersin the frequency domain. For reference, a resource composed by an OFDMsymbol and a subcarrier is called a resource element (RE) or a tone.Accordingly, an RB is composed of N_(symb) ^(DL/UL)*N_(sc) ^(RB) REs.Each RE in a resource grid can be uniquely defined by an index pair(k, 1) in a slot. Here, k is an index in the range of 0 to N_(symb)^(DL/UL)*N_(sc) ^(RB)−1 in the frequency domain and 1 is an index in therange of 0 to N_(symb) ^(DL/UL)−1.

Two RBs that occupy N_(sc) ^(RB) consecutive subcarriers in a subframeand respectively disposed in two slots of the subframe are called aphysical resource block (PRB) pair. Two RBs constituting a PRB pair havethe same PRB number (or PRB index). A virtual resource block (VRB) is alogical resource allocation unit for resource allocation. The VRB hasthe same size as that of the PRB. The VRB may be divided into alocalized VRB and a distributed VRB depending on a mapping scheme of VRBinto PRB. The localized VRBs are mapped into the PRBs, whereby VRBnumber (VRB index) corresponds to PRB number. That is, nPRB=nVRB isobtained. Numbers are given to the localized VRBs from 0 to N_(VRB)^(DL)−1, and N_(VRB) ^(DL)=N_(RB) ^(DL) is obtained. Accordingly,according to the localized mapping scheme, the VRBs having the same VRBnumber are mapped into the PRBs having the same PRB number at the firstslot and the second slot. On the other hand, the distributed VRBs aremapped into the PRBs through interleaving. Accordingly, the VRBs havingthe same VRB number may be mapped into the PRBs having different PRBnumbers at the first slot and the second slot. Two PRBs, which arerespectively located at two slots of the subframe and have the same VRBnumber, will be referred to as a pair of VRBs.

FIG. 3 illustrates a downlink (DL) subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 3, a DL subframe is divided into a control region anda data region. A maximum of three (four) OFDM symbols located in a frontportion of a first slot within a subframe correspond to the controlregion to which a control channel is allocated. A resource regionavailable for PDCCH transmission in the DL subframe is referred to as aPDCCH region hereinafter. The remaining OFDM symbols correspond to thedata region to which a physical downlink shared chancel (PDSCH) isallocated. A resource region available for PDSCH transmission in the DLsubframe is referred to as a PDSCH region hereinafter. Examples ofdownlink control channels used in 3GPP LTE include a physical controlformat indicator channel (PCFICH), a physical downlink control channel(PDCCH), a physical hybrid ARQ indicator channel (PHICH), etc. ThePCFICH is transmitted at a first OFDM symbol of a subframe and carriesinformation regarding the number of OFDM symbols used for transmissionof control channels within the subframe. The PHICH is a response ofuplink transmission and carries an HARQ acknowledgment (ACK)/negativeacknowledgment (NACK) signal.

Control information carried on the PDCCH is called downlink controlinformation (DCI). The DCI contains resource allocation information andcontrol information for a UE or a UE group. For example, the DCIincludes a transport format and resource allocation information of adownlink shared channel (DL-SCH), a transport format and resourceallocation information of an uplink shared channel (UL-SCH), paginginformation of a paging channel (PCH), system information on the DL-SCH,information about resource allocation of an upper layer control messagesuch as a random access response transmitted on the PDSCH, a transmitcontrol command set with respect to individual UEs in a UE group, atransmit power control command, information on activation of a voiceover IP (VoIP), downlink assignment index (DAI), etc. The transportformat and resource allocation information of the DL-SCH are also calledDL scheduling information or a DL grant and the transport format andresource allocation information of the UL-SCH are also called ULscheduling information or a UL grant. The size and purpose of DCIcarried on a PDCCH depend on DCI format and the size thereof may bevaried according to coding rate. Various formats, for example, formats 0and 4 for uplink and formats 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3 and 3Afor downlink, have been defined in 3GPP LTE. Control information such asa hopping flag, information on RB allocation, modulation coding scheme(MCS), redundancy version (RV), new data indicator (NDI), information ontransmit power control (TPC), cyclic shift demodulation reference signal(DMRS), UL index, channel quality information (CQI) request, DLassignment index, HARQ process number, transmitted precoding matrixindicator (TPMI), precoding matrix indicator (PMI), etc. is selected andcombined based on DCI format and transmitted to a UE as DCI.

In general, a DCI format for a UE depends on transmission mode (TM) setfor the UE. In other words, only a DCI format corresponding to aspecific TM can be used for a UE configured in the specific TM.

A PDCCH is transmitted on an aggregation of one or several consecutivecontrol channel elements (CCEs). The CCE is a logical allocation unitused to provide the PDCCH with a coding rate based on a state of a radiochannel. The CCE corresponds to a plurality of resource element groups(REGs). For example, a CCE corresponds to 9 REGs and an REG correspondsto 4 REs. 3GPP LTE defines a CCE set in which a PDCCH can be located foreach UE. A CCE set from which a UE can detect a PDCCH thereof is calleda PDCCH search space, simply, search space. An individual resourcethrough which the PDCCH can be transmitted within the search space iscalled a PDCCH candidate. A set of PDCCH candidates to be monitored bythe UE is defined as the search space. In 3GPP LTE/LTE-A, search spacesfor DCI formats may have different sizes and include a dedicated searchspace and a common search space. The dedicated search space is aUE-specific search space and is configured for each UE. The commonsearch space is configured for a plurality of UEs. Aggregation levelsdefining the search space is as follows.

TABLE 3 Search Space Aggregation Size [in Number of PDCCH Type Level LCCEs] candidates M^((L)) UE-specific 1 6 6 2 12 6 4 8 2 8 16 2 Common 416 4 8 16 2

A PDCCH candidate corresponds to 1, 2, 4 or 8 CCEs according to CCEaggregation level. An eNB transmits a PDCCH (DCI) on an arbitrary PDCCHcandidate with in a search space and a UE monitors the search space todetect the PDCCH (DCI). Here, monitoring refers to attempting to decodeeach PDCCH in the corresponding search space according to all monitoredDCI formats. The UE can detect the PDCCH thereof by monitoring pluralPDCCHs. Since the UE does not know the position in which the PDCCHthereof is transmitted, the UE attempts to decode all PDCCHs of thecorresponding DCI format for each subframe until a PDCCH having the IDthereof is detected. This process is called blind detection (or blinddecoding (BD)).

The eNB can transmit data for a UE or a UE group through the dataregion. Data transmitted through the data region may be called userdata. For transmission of the user data, a physical downlink sharedchannel (PDSCH) may be allocated to the data region. A paging channel(PCH) and downlink-shared channel (DL-SCH) are transmitted through thePDSCH. The UE can read data transmitted through the PDSCH by decodingcontrol information transmitted through a PDCCH. Informationrepresenting a UE or a UE group to which data on the PDSCH istransmitted, how the UE or UE group receives and decodes the PDSCH data,etc. is included in the PDCCH and transmitted. For example, if aspecific PDCCH is CRC (cyclic redundancy check)-masked having radionetwork temporary identify (RNTI) of “A” and information about datatransmitted using a radio resource (e.g., frequency position) of “B” andtransmission format information (e.g., transport block size, modulationscheme, coding information, etc.) of “C” is transmitted through aspecific DL subframe, the UE monitors PDCCHs using RNTI information anda UE having the RNTI of “A” detects a PDCCH and receives a PDSCHindicated by “B” and “C” using information about the PDCCH.

A reference signal (RS) to be compared with a data signal is necessaryfor the UE to demodulate a signal received from the eNB. A referencesignal refers to a predetermined signal having a specific waveform,which is transmitted from the eNB to the UE or from the UE to the eNBand known to both the eNB and UE. The reference signal is also called apilot. Reference signals are categorized into a cell-specific RS sharedby all UEs in a cell and a modulation RS (DM RS) dedicated for aspecific UE. A DM RS transmitted by the eNB for demodulation of downlinkdata for a specific UE is called a UE-specific RS. Both or one of DM RSand CRS may be transmitted on downlink. When only the DM RS istransmitted without CRS, an RS for channel measurement needs to beadditionally provided because the DM RS transmitted using the sameprecoder as used for data can be used for demodulation only. Forexample, in 3GPP LTE(-A), CSI-RS corresponding to an additional RS formeasurement is transmitted to the UE such that the UE can measurechannel state information. CSI-RS is transmitted in each transmissionperiod corresponding to a plurality of subframes based on the fact thatchannel state variation with time is not large, unlike CRS transmittedper subframe.

FIG. 4 illustrates an exemplary uplink subframe structure used in 3GPPLTE/LTE-A.

Referring to FIG. 4, a UL subframe can be divided into a control regionand a data region in the frequency domain. One or more PUCCHs (physicaluplink control channels) can be allocated to the control region to carryuplink control information (UCI). One or more PUSCHs (Physical uplinkshared channels) may be allocated to the data region of the UL subframeto carry user data.

In the UL subframe, subcarriers spaced apart from a DC subcarrier areused as the control region. In other words, subcarriers corresponding toboth ends of a UL transmission bandwidth are assigned to UCItransmission. The DC subcarrier is a component remaining unused forsignal transmission and is mapped to the carrier frequency f0 duringfrequency up-conversion. A PUCCH for a UE is allocated to an RB pairbelonging to resources operating at a carrier frequency and RBsbelonging to the RB pair occupy different subcarriers in two slots.Assignment of the PUCCH in this manner is represented as frequencyhopping of an RB pair allocated to the PUCCH at a slot boundary. Whenfrequency hopping is not applied, the RB pair occupies the samesubcarrier.

The PUCCH can be used to transmit the following control information.

-   -   Scheduling Request (SR): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ ACK/NACK: This is a response signal to a downlink data        packet on a PDSCH and indicates whether the downlink data packet        has been successfully received. A 1-bit ACK/NACK signal is        transmitted as a response to a single downlink codeword and a        2-bit ACK/NACK signal is transmitted as a response to two        downlink codewords. HARQ-ACK responses include positive ACK        (ACK), negative ACK (NACK), discontinuous transmission (DTX) and        NACK/DTX. Here, the term HARQ-ACK is used interchangeably with        the term HARQ ACK/NACK and ACK/NACK.    -   Channel State Indicator (CSI): This is feedback information        about a downlink channel. Feedback information regarding MIMO        includes a rank indicator (RI) and a precoding matrix indicator        (PMI).

The quantity of control information (UCI) that a UE can transmit througha subframe depends on the number of SC-FDMA symbols available forcontrol information transmission. The SC-FDMA symbols available forcontrol information transmission correspond to SC-FDMA symbols otherthan SC-FDMA symbols of the subframe, which are used for referencesignal transmission. In the case of a subframe in which a soundingreference signal (SRS) is configured, the last SC-FDMA symbol of thesubframe is excluded from the SC-FDMA symbols available for controlinformation transmission. A reference signal is used to detect coherenceof the PUCCH. The PUCCH supports various formats according toinformation transmitted thereon.

Table 4 shows the mapping relationship between PUCCH formats and UCI inLTE/LTE-A.

TABLE 4 Number of bits per PUCCH Modulation subframe, format schemeM_(bit) Usage Etc. 1  N/A N/A SR (Scheduling Request) 1a BPSK 1 ACK/NACKor One SR + ACK/ codeword NACK 1b QPSK 2 ACK/NACK or Two SR + ACK/codeword NACK 2  QPSK 20 CQI/PMI/RI Joint coding ACK/NACK (extended CP)2a QPSK + 21 CQI/PMI/RI + Normal CP BPSK ACK/NACK only 2b QPSK + 22CQI/PMI/RI + Normal CP QPSK ACK/NACK only 3  QPSK 48 ACK/NACK or SR +ACK/ NACK or CQI/PMI/RI + ACK/NACK

Referring to Table 4, PUCCH formats 1/1a/1b are used to transmitACK/NACK information, PUCCH format 2/2a/2b are used to carry CSI such asCQI/PMI/RI and PUCCH format 3 is used to transmit ACK/NACK information.

Reference Signal (RS)

When a packet is transmitted in a wireless communication system, signaldistortion may occur during transmission since the packet is transmittedthrough a radio channel. To correctly receive a distorted signal at areceiver, the distorted signal needs to be corrected using channelinformation. To detect channel information, a signal known to both atransmitter and the receiver is transmitted and channel information isdetected with a degree of distortion of the signal when the signal isreceived through a channel. This signal is called a pilot signal or areference signal.

When data is transmitted/received using multiple antennas, the receivercan receive a correct signal only when the receiver is aware of achannel state between each transmit antenna and each receive antenna.Accordingly, a reference signal needs to be provided per transmitantenna, more specifically, per antenna port.

Reference signals can be classified into an uplink reference signal anda downlink reference signal. In LTE, the uplink reference signalincludes:

i) a demodulation reference signal (DMRS) for channel estimation forcoherent demodulation of information transmitted through a PUSCH and aPUCCH; and

ii) a sounding reference signal (SRS) used for an eNB to measure uplinkchannel quality at a frequency of a different network.

The downlink reference signal includes:

i) a cell-specific reference signal (CRS) shared by all UEs in a cell;

ii) a UE-specific reference signal for a specific UE only;

iii) a DMRS transmitted for coherent demodulation when a PDSCH istransmitted;

iv) a channel state information reference signal (CSI-RS) for deliveringchannel state information (CSI) when a downlink DMRS is transmitted;

v) a multimedia broadcast single frequency network (MBSFN) referencesignal transmitted for coherent demodulation of a signal transmitted inMBSFN mode; and

vi) a positioning reference signal used to estimate geographic positioninformation of a UE.

Reference signals can be classified into a reference signal for channelinformation acquisition and a reference signal for data demodulation.The former needs to be transmitted in a wide band as it is used for a UEto acquire channel information on downlink transmission and received bya UE even if the UE does not receive downlink data in a specificsubframe. This reference signal is used even in a handover situation.The latter is transmitted along with a corresponding resource by an eNBwhen the eNB transmits a downlink signal and is used for a UE todemodulate data through channel measurement. This reference signal needsto be transmitted in a region in which data is transmitted.

The present specification proposes a method of defining a subchannel bydividing radio resources in time and frequency domains and a method offorming a physical channel for transmitting information and data by abundle of subchannels. In particular, a data channel is formed bycombining a plurality of subchannels to transmit data.

According to the proposed method, subchannels are used in a manner ofbeing divided between adjacent transmission nodes to minimize mutualinterference and an interference amount provided to a subchannel isuniformly maintained to make transmission capacity in each node to bemaximized. According to the proposed transmission scheme, a transmissionnode occupies a resource for a prescribed time in a unit of a subchannelto transmit a signal.

The proposed scheme of the present invention is explained centering on acommunication link between an eNB and a UE in a cellular system. Yet,the proposed scheme can be applied to a communication link between UEsas well.

[Definition of Subchannel]

The total radio resources are divided into subchannels (SCs) using acombination of a subband and a subframe in a manner that a transmissionband is divided into a plurality of subbands (SBs) and a transmissionradio frame is divided into a plurality of subframes (SFs). A subbandcan be configured by a plurality of subcarriers and a subframe can beconfigured by a plurality of OFDM symbols in a manner of being combinedwith OFDM transmission scheme.

FIG. 5 shows an example that the total radio resources are divided into80 subchannels using 10 radio transmission bands and 8 radio frames. InFIG. 5, resources represented by a slashed shape correspond tosubchannels generated by combining a 3^(rd) subband (SB3) and a 2^(nd)subframe (SF2). In the following, a subchannel generated by combining ani^(th) subband and j^(th) subframe is represented as SC (i,j).

A subchannel structure of an interleaved pattern shown in FIG. 5 has acharacteristic capable of easily applying a stop and wait HRAQ operationfor data transmission. In FIG. 5, whether a previous data isretransmitted or a new data is transmitted in an (i+1)^(th) frame isdetermined according to whether or not data transmitted from an i^(th)frame is successfully received. The subchannel structure shown in FIG. 5enables data transmitted on a subchannel to be managed using a singleHARQ process.

[Data Channel and Feedback Channel]

In the following, the present invention is explained in the aspect of DLthat data is transmitted from an eNB to a UE in a cellular system.

As a physical channel, it is necessary to have a data channel fortransmitting data and a control channel for transmitting controlinformation to indicate a data transmission format. And, in order tosend ACK/NACK response for a HARQ operation of the data channel or inorder to feedback CQI (channel quality indication) for determining MCS(modulation and coding scheme) of a data channel, it is necessary tohave a feedback channel from a receiving node. In case of an FDD system,the feedback channel is transmitted via a reverse direction link locatedat a different frequency band. In case of a TDD system, the feedbackchannel is transmitted at a different timing of the same frequency band.

FIG. 6 shows an example that a data channel (DCH) is formed by an SC(3,2) and a feedback channel is formed by an SC (3,6) in a TDD system.In FIG. 6 and following drawings, a control channel is not separatelydrawn in consideration of a case that the control channel and the datachannel are transmitted in a manner of being multiplexed on the samesubchannel.

In general, a data mount transmitted on a data channel is considerablylarger than an information amount transmitted on a feedback channel.Hence, the number of subchannels for configuring the data channel andthe number of subchannels for configuring the feedback channel can bedifferently configured.

FIG. 7 shows an example that a data channel is formed by 8 subbandsincluding an SC (3,2) to an SC (10,2) and a feedback channel is formedby a single subband SC (3,6) in a TDD system. Unlike the data channelshown in FIG. 7, a data channel can also be configured by subchannels ofa discontinuous subband. Moreover, a data channel can also be configuredusing subchannels over a plurality of subframes.

In order to increase a data transmission rate of a link between an eNBand a UE, it may be able to form a plurality of data channels andtransmit data using the same. Each of a plurality of the data channelscan be located at a different subband or a different subframe. Accordingto the proposed scheme, a data channel and a feedback channel areconfigured to make a pair.

A transmission timing of a data channel and a transmission timing of afeedback channel can be defined with a predetermined difference. Inparticular, if the data channel is transmitted in an n^(th) subframe,the feedback channel can be fixed to respond in an (n+d)^(th) subframe.

FIG. 8 shows an example for a case that a feedback channel is fixed torespond in an (n+4)^(th) subframe in response to a data channel which istransmitted in an n^(th) subframe in a TDD system. According to anembodiment of the present invention, 3 data channels are set to acorresponding link to transmit data. In the drawing, a UE makes aresponse by a feedback channel FCH1 in a 6^(th) subframe in response toa data channel DCH1 which is transmitted in a 2^(nd) subframe. And, theUE makes a response by a feedback channel FCH2 in a 7^(th) subframe inresponse to a data channel DCH2 which is transmitted in a 3^(rd)subframe. According to the embodiment of the present invention, anindependent HARQ process is managed in each data channel. In particular,assume that there exist 3 HARQ processes in total. Since it is able toindependently configure subbands that construct each data channel, incase of a data channel DCH3, the data channel may have a narrowertransmission band compared to data channels DCH1 and the DCH2.

Referring to FIG. 8, since a scheme of utilizing a fixed space between adata channel and a feedback channel uses only the half of totalsubframes in transmitting data channels in a TDD system, the scheme hasa demerit in that a data transmission efficiency is low. However, sincea fixed space is able to definitely guarantee time required forreception processing such as data channel decoding of a UE, and the likeand time required for transmission processing of an eNB, it may have amerit in that implementation is easy. Hence, the scheme of utilizing afixed space between a data channel and a feedback channel has the greatadvantage especially in a FDD system.

When a data channel is configured, it may consider a variable schemethat configures a relative position of a feedback channel. An eNBdesignates subchannels used as a feedback channel of a UE whileinforming the UE of subchannels used as a data channel. In order to makethe UE easily implement reception processing, it may be able to set alimit on subchannel positions to which a feedback channel isconfigurable.

FIG. 9 shows an example of a resource region of a feedback channelcapable of being configured in response to a resource position of a datachannel in the variable scheme. Referring to FIG. 9, a feedback channelis transmitted in an (n+d)^(th) subframe in response to a data channeltransmitted in an n^(th) subframe. In this case, the d can be selectedfrom among 3, 4, 5, and 6. A minimum value of the space d between thedata channel and the feedback channel should be configured to be largerthan time required for a receiver to perform reception processing suchas data channel decoding and the like. A maximum value of the space dshould be configured in consideration of time required for a transmitterto receive ACK/NACK feedback and time required for the transmitter toprepare data transmission. The embodiment of FIG. 9 shows an availableregion of a feedback channel when the receiver requires minimum 2subframes for reception processing and the transmitter requires minimum1 subframe for transmission processing.

A subband on which a feedback channel is transmitted is designatedwithin a determined range. This is intended to configure the feedbackchannel within a maximum bandwidth capable of being supported by atransmitter. In particular, if there is a limit on a reception bandwidthdue to capability of a UE, the number of subbands of a data channel setto the UE is configured to be set within a bandwidth capable of beingmaximally supported. As a result, a location to which the feedbackchannel is set is configured to be set within the bandwidth.

FIG. 10 shows a case that 3 data channels are set to a correspondinglink to transmit data in a variable scheme. FIG. 10 shows an examplethat a resource of a feedback channel corresponding to each data channelis matched to transmit feedback channels FCH1, FCH2, and FCH3 on thesame subchannel in a manner of multiplexing the feedback channels. InFIG. 10, a space d between a data channel DCH1 and a feedback channelFCH1 is configured by 5, a space d between a data channel DCH2 and afeedback channel FCH2 is configured by 4, and a space d between a datachannel DCH3 and a feedback channel FCH3 is configured by 3. As shown inthe embodiment of FIG. 9, if there is a limit on a range of the space d,maximum 75% of the total subframes can be used for transmitting datachannel in a TDD system.

If a frame is divided into N number of subframes and each subchannelrepeatedly appears in every N number of subframes, a space d between adata channel and a feedback channel should be configured to be smallerthan N. However, this constraint may limit flexibility of resourceutilization in a TDD system. Hence, the present invention proposes amethod of managing a case that the space d is greater than the N.

FIG. 11 shows a method of managing a single data channel by two HARQprocesses. According to the proposed method, a data channel is managedby two HARQ processes in a manner of being divided into a HARQ process 1and a HARQ process 2. Referring to the example shown in FIG. 11,ACK/NACK feedback is transmitted in an SF6 of (i+1)^(th) frame appearingafter d=12 subframe in response to data transmitted in an SF2 of ani^(th) frame. In the example, if a receiver fails to properly decode thedata transmitted in the SF2 of the i^(th) frame, the data isretransmitted in an SF2 of (i+2)^(th) frame.

According to the proposed scheme, if a feedback channel is configuredwithin a feedback channel resource region (i.e., if d is designatedbetween 3 and 6), a single data channel is managed by a single HARQprocess. If the d is designated between 7 and 14, a single data channelis managed by two HARQ processes. If the space d is equal to or greaterthan 14, a single data channel is managed by two or more HARQ processes.

As a different management method, FIG. 12 shows a method that atransmission interval of a data channel is selected from among N and 2N.According to the proposed method, the transmission interval of the datachannel can be adjusted according to the space d between the datachannel and the feedback channel. If a feedback channel is configuredwithin a feedback channel resource region shown in FIG. 9 (i.e., if d isdesignated between 3 and 6), a data channel is transmitted in every Nnumber of subframes. If the d is designated between 7 and 14, a datachannel is transmitted in every 2N number of subframes. In a broadsense, if the d is equal to or greater than 14, a data channel istransmitted in every N multiple number of subframes. This managementscheme is identical to the method of forming a data channel according toa HARQ process mentioned in FIG. 11.

[Grant Channel and Data Channel]

In the following, a method of dividing radio resources is explained inthe aspect of UL (uplink) that data is transmitted from a UE to an eNBin a cellular system. It may be able to consider two procedures fortransmitting UL data.

A first procedure corresponds to a scheme that a UE determines a dataamount, a transmission format such as MCS, and the like to transmitdata. In this case, the UE transmits a control channel together with adata channel. And, an eNB transmits ACK/NACK information and CQIinformation on a feedback channel in response to the data channel andthe control channel. This procedure is identical to a case that a UEplays a role of an eNB and the eNB plays role of the UE in DLtransmission scheme. Hence, the DL embodiments shown in FIG. 6 to FIG.12 can be applied to UL as it is.

Meanwhile, a second procedure corresponds to a scheme that an eNBdetermines whether to transmit UL data and a transmission format andinforms a UE of a result of the determination. The eNB informs the UE ofa data amount, a UL data transmission format such as MCS, and the like,and information on whether or not ACK/NACK is transmitted in response toa previously transmitted data. By doing so, the eNB can indicate the UEto retransmit the previous data or transmit a new data. FIG. 13 shows anembodiment that the eNB forwards information on whether or not the UEtransmits data and format information to the UE via a grant channel andthe UE transmits a data channel in a predetermined resource based on theinformation received from the eNB.

Similar to DL, in order to increase a data transmission rate in UL, aplurality of data channels are formed on a link between a UE and an eNBand the UE transmits data using the data channels. Each of a pluralityof the data channels can be located at a different subband or adifferent subframe. According to the proposed scheme, a grant channeland a data channel are configured to make a pair.

A transmission timing of a grant channel and a transmission timing of adata channel can be defined by a fixed space scheme for defining thetimings with a predetermined difference or a variable space scheme fordefining the timings with a space between two channels. According to thefixed space scheme, a data channel is transmitted in (n+d)^(th) subframein response to a grant channel which is transmitted in an n^(th)subframe. In this case, the d is defined in advance to make a fixedspace exist between all pairs of the grant channel and the data channel.According to the variable space scheme, when a data channel isconfigured, a relative position compared to grant channel transmissiontiming can be selected from among available values to configure the datachannel. FIG. 14 shows an example of a resource region of a data channelcapable of being configured in relation to a resource position of agrant channel in the variable space scheme. In FIG. 14, a data channelis transmitted in (n+d)^(th) subframe according to indication of a grantchannel transmitted in an n^(th) subframe. In this case, the d can bedesignated from among 2, 3, 4 and 5. The embodiment of FIG. 14 shows aregion capable of transmitting a data channel when a UE requires minimum1 subframe for data transmission processing after a grant channel isreceived and an eNB requires minimum 2 subframes for data receptionprocessing.

FIG. 15 illustrates a case that 3 data channels are set to acorresponding link to transmit data in a variable scheme. FIG. 15 showsan example that a resource of a grant channel corresponding to each datachannel is matched to transmit grant channels GCH1, GCH2, and GCH3 onthe same subchannel in a manner of multiplexing the grant channels. InFIG. 15, a space d of a data channel DCH1 is configured by 2, a space dof a data channel DCH2 is configured by 3, and a space d of a datachannel DCH3 is configured by 4 in comparison with a grant channel.

If each subchannel is configured to repeatedly appear in every N numberof subframes, a space d between a grant channel and a data channelshould be configured to be smaller than N. However, this constraint maylimit flexibility of resource utilization in a TDD system. Hence, if thespace d is greater than N, as shown in FIG. 16, it may be able to use ascheme of managing a single data channel by two HARQ processes.Referring to an example of FIG. 16, for instance, data is transmitted inan SF3 of (i+1)^(th) frame appearing after d=9 subframe in response to agrant of HARQ process 1 transmitted in an SF2 of an i^(th) frame.Consequently, the method proposed in the present embodiment is identicalto a method of defining a data channel according to a HARQ process andselecting a transmission interval of the data channel from among N and2N.

[Common Data Channel and Dedicated Data Channel]

Data channels can be divided into a common data channel and a dedicateddata channel. In order to transceive small amount of data between an eNBand a UE, it may use a common data channel. In order to transceive largeamount of data between the eNB and the UE, it may configure a dedicateddata channel and can transmit the data via the dedicated data channel.Basically, a common channel is configured between the eNB and the UE. Ifa data amount to be transmitted increases, information for configuring adedicated data channel is transmitted to the UE via the common channel.

The information for configuring the dedicated data channel can includethe number of data channels, the number of subchannels included in eachdata channel, and a resource position. In case of DL, the informationcan include the number of subchannels included in a feedback channelcorresponding to each data channel and a resource position. In case ofUL, the information can include the number of subchannels included in agrant channel corresponding to each data channel and a resourceposition. When a configuration of the dedicated data channel is changed,it may change the configuration of the dedicated data channel via acommon data channel or a predetermined dedicated data channel.

In case of DL, a common data channel may correspond to a channel atwhich a UE receiving forwarded data changes. Hence, a control channel,which is transmitted together with the common data channel in everysubframe, includes information on a UE to which the data is forwarded.On the contrary, in case of a DL dedicated data channel, when the DLdedicated channel is configured, a UE to be used for the DL dedicatedchannel is determined. Hence, it is not necessary to include informationon the UE in a control channel which is transmitted together with thededicated data channel.

In case of UL, a common data channel may correspond to a channel atwhich a UE transmitting data changes. Hence, a grant channel, which isconnected with the common data channel, includes information on a UE totransmit data using the common data channel. On the contrary, in case ofa UL dedicated data channel, when the UL dedicated data channel isconfigured, a UE to be used for the UL dedicated data channel isdetermined. Hence, it is not necessary to designate a UE to transmitdata using the grant channel.

In case of a common data channel, a UE using the channel may changewhenever data is transmitted. If there is no UE to use the common datachannel, no signal is transmitted on the channel. Hence, in the aspectof a neighboring eNB on subchannels constructing the common datachannel, an interference amount is not fixed. On the contrary, adedicated data channel is seamlessly used for transmitting data from thestart of configuration to the end of the configuration of the dedicateddata channel. In this case, in the aspect of a neighboring eNB onsubchannels constructing the dedicated data channel, an interferenceamount is uniformly maintained, thereby increasing adaptation efficiencyof a transmission data rate.

In order to evenly maintain an interference amount provided to aneighboring cell, a dedicated data channel can be configured only whendata are continuously transmitted more than prescribed times onsubchannels or when data are sufficiently buffered in a transmissionbuffer to continuously use a corresponding resource for more thanprescribed time. If there is no data to be transmitted anymore and nosignal is transmitted on a subchannel, the configuration of thededicated data channel is released.

An eNB determines a region to be used for a common channel and a regionto be used for a dedicated channel in advance among total radioresources, i.e., subchannels. The eNB informs a neighboring eNB of thedetermined regions.

FIG. 17 shows an example that a radio resource is divided into a regionfor a DL common data channel (DL-CDCH), a region for a DL dedicated datachannel (DL-DDCH), a region for a UL common data channel (UL-CDCH), anda region for a UL dedicated data channel (UL-DDCH). In FIG. 17, afeedback channel is not separately drawn under the assumption that thefeedback channel uses the UL-CDCH region when the feedback channel makesa pair with a common data channel and uses subchannels of the UL-DDCHregion when the feedback channel makes a pair with a dedicated datachannel. Similarly, a grant channel is not separately drawn under theassumption that the grant channel uses the DL-CDCH region when the grantchannel makes a pair with a common data channel and uses subchannels ofthe DL-DDCH region when the grant channel makes a pair with a dedicateddata channel.

As a variation, a resource size of a common data channel can be definedin advance. A corresponding position can be informed only between eNBs.And, a resource position of UL-CDCH can be defined in advance based on apositon of DL-CDCH.

An object of the proposed scheme is to inform a neighboring eNB of aregion at which interference provided to the neighboring eNB isuniformly maintained and a region at which an interference amount ischanged at every transmission timings, respectively. In particular, theobject of the proposed scheme is to inform the neighboring eNB of aregion at which signal transmission is evenly maintained for prescribedtime and a region at which a direction of a transmission beam is notmaintained in MIMO transmission, respectively. Hence, it may be able todirectly inform the neighboring eNB of a region at which transmission isconstantly performed and a region at which transmission is irregularlyperformed, respectively, instead of informing the neighboring eNB ofpositions to which a common channel and a dedicated channel are set.

In addition, a resource region of a dedicated data channel can bedivided into a plurality of regions. In this case, it may be able toinform a neighboring eNB of use priority of each of a plurality of theregions. A subchannel of high priority can be assigned first as adedicated data channel. The neighboring eNB can determine whether or nota resource position is interfered by interference based on theadditional information. If each cell does not use the total radioresources due to low loading in each cell, inter-cell interference canbe minimized by making a mutually used radio resource not to beoverlapped between cells. By doing so, it is able to efficiently controlthe inter-cell interference.

In order to control the inter-cell interference, information isexchanged between eNBs via a wired or wireless backhaul. If there is alimit on an information amount exchanged via the wired/wirelessbackhaul, it may be able to exchange attributes of the aforementionedcommon data channel region, the dedicated data channel region, and thepriority of each region. Meanwhile, if speed of the informationexchanged via the wired/wireless backhaul is very fast, it may be ableto configure a dedicated data channel and inform a neighboring eNB ofthe dedicated data channel in real time. Or, if the informationexchanged via the backhaul has a delay in some extent, configurationexpectation information on a dedicated data channel can be transmittedto a neighboring eNB together with information on expectation timing.

[Listen Before Occupy]

In the present paragraph, a method of controlling interference using anLBO (listen before occupy) operation is proposed when informationexchange for controlling inter-cell interference via backhaul betweeneNBs is impossible. According to the proposed method, each eNB measuresan interference amount or a signal transmitted from a neighboring cellon subchannels capable of being selected by the eNB to configure adedicated data channel. Subsequently, the eNB selects subchannels forconstructing a dedicated data channel according to a measurement result.As an embodiment, the eNB measures an interference amount from eachsubchannel to configure a data channel using a subchannel of lessinterference amount. Or, the eNB may randomly select a subchannel fromamong subchannels that an interference amount is equal to or less than aprescribed level or subchannels that a signal transmitted from aneighboring cell is received with a level equal to or less than aspecific level to configure a data channel.

For an initial access or handover of a UE in a general cellular system,an eNB transmits a synchronization signal and a measurement signal. Inthe present invention, the synchronization signal and the measurementsignal can also be transmitted using a part of a resource region of a DLcommon data channel. According to the proposed method, when an eNB isturned on, the eNB receives a synchronization signal and a measurementsignal from a neighboring eNB, matches time synchronization with theneighboring eNB, and identifies a position of the DL common data channelof the neighboring eNB. And, the eNB determines a transmission resourceposition of the DL common data channel in consideration of positions ofDL common data channel resources of neighboring eNBs. In this case, aposition of a UL common data channel resource can be predefined to beknown from the position of the DL common data channel resource. And,sizes of the DL and UL common data channel resources can be defined inadvance.

Unlikely, when system information is informed via a broadcast channel ofthe DL common data channel, the positions and the sizes of the DL andthe UL common data channel resources can be informed. In this case, itis able to know a position and a size of a common channel by receivingsystem information of a neighboring eNB.

[CSI Feedback]

According to the proposed scheme, since each cell uses a radio resourcein a subchannel unit, there may exist a difference in an interferenceamount according to a subchannel. In particular, a difference inreception quality between data channels is represented according to asubchannel due to a difference between interference amounts. In order toobtain optimized transmission capacity in the aforementionedenvironment, CQI is fed back according to a subchannel and atransmission MCS can be controlled according to a subchannel. In orderto differentiate the MCS according to a subchannel, data to betransmitted are divided according to a subchannel and coding and ratematching are differentiated according to each data block to transmitdata according to an MCS selected on a corresponding subchannel.Meanwhile, it may be able to feedback CQI according to a data channeland control a transmission MCS in consideration of overhead of controlinformation and feedback information.

CSI including CQI is transmitted on a feedback channel together withACK/NACK. In order to reduce feedback overhead, it may be able to reporta difference of an MCS level capable of being supported in considerationof CQI compared to an MCS level which is used in a previous transmissiontogether with ACK/NACK for the previous data transmission. Table 5 showsan example that ACK/NACK and CQI are fed back in a manner of beingcombined to differently interpret CQI information according to ACK/NACK.

TABLE 5 HARQ-ACK bundled with CQI feedback A/N CQI 00 A Request to keepMCS 01 A Request to increase MCS 10 N Request to keep MCS 11 N Requestto decrease MCS

[UE Capability]

According to the proposed scheme, a UE can inform an eNB of followingitems as UE capability.

-   -   Number of data channels capable of being supported at the same        time    -   Maximum supportable bandwidth    -   Maximum number of subchannels constructing data channel    -   Maximum number of bits capable of being transmitted per data        channel

FIG. 18 is a flowchart for an operation according to one embodiment ofthe present invention.

FIG. 18 relates to a method of controlling interference in a radioresource consisting of a plurality of bands and a plurality of frames.

An eNB 181 can allocate a dedicated data channel for a specific UE and acommon data channel for a plurality of UEs [S1810]. The eNB can forwardinformation on the allocated dedicated data channel and the common datachannel to a neighboring eNB 182 [S1820]. The dedicated data channel canbe allocated when data to be transmitted to the specific UE, which isstanding by in a transmission buffer, is greater than a predeterminedamount.

The information on the dedicated data channel can include the number ofthe dedicated data channel, the number of subchannels included in eachdedicated data channel, and a resource position of each dedicated datasubchannel.

The information on the dedicated data channel can include the number ofsubchannels included in a feedback channel or a grant channel connectedwith each dedicated data channel and a resource position of eachdedicated feedback subchannel.

The number of HARQ (hybrid automatic request transmission) processes ofthe dedicated data channel can be determined according to a spacebetween the dedicated data channel and a feedback channel or a grantchannel associated with the dedicated data channel.

A transmission interval of the dedicated data channel can be determinedaccording to a time interval between the dedicated data channel and afeedback channel or a grant channel associated with the dedicated datachannel.

A plurality of feedback channels or grant channels associated with aplurality of dedicated data channels can be assigned to a singlesubchannel in a manner of being multiplexed.

The eNB 181 can forward information on use priority of a plurality ofsubchannels constructing the dedicated data channel to the neighboringeNB 182. The eNB can allocate the dedicated data channel according tothe use priority.

The eNB 181 can receive information on a dedicated data channel and acommon data channel allocated for UEs of the neighboring eNB from theneighboring eNB 182.

The dedicated data channel allocated for the specific UE and the commondata channel allocated for a plurality of the UEs can be allocated basedon the information on the dedicated data channel and the common datachannel allocated for the UEs of the neighboring eNB received from theneighboring eNB.

The operation of the UE or the eNB shown in FIG. 18 can include not onlythe embodiment mentioned earlier with reference to FIG. 18, but also atleast one of the aforementioned embodiments of the present invention.

FIG. 19 is a block diagram of a transmitting device 10 and a receivingdevice 20 configured to implement exemplary embodiments of the presentinvention. Referring to FIG. 19, the transmitting device 10 and thereceiving device 20 respectively include radio frequency (RF) units 13and 23 for transmitting and receiving radio signals carryinginformation, data, signals, and/or messages, memories 12 and 22 forstoring information related to communication in a wireless communicationsystem, and processors 11 and 21 connected operationally to the RF units13 and 23 and the memories 12 and 22 and configured to control thememories 12 and 22 and/or the RF units 13 and 23 so as to perform atleast one of the above-described embodiments of the present invention.

The memories 12 and 22 may store programs for processing and control ofthe processors 11 and 21 and may temporarily storing input/outputinformation. The memories 12 and 22 may be used as buffers. Theprocessors 11 and 21 control the overall operation of various modules inthe transmitting device 10 or the receiving device 20. The processors 11and 21 may perform various control functions to implement the presentinvention. The processors 11 and 21 may be controllers,microcontrollers, microprocessors, or microcomputers. The processors 11and 21 may be implemented by hardware, firmware, software, or acombination thereof. In a hardware configuration, Application SpecificIntegrated Circuits (ASICs), Digital Signal Processors (DSPs), DigitalSignal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), orField Programmable Gate Arrays (FPGAs) may be included in the processors11 and 21. If the present invention is implemented using firmware orsoftware, firmware or software may be configured to include modules,procedures, functions, etc. performing the functions or operations ofthe present invention. Firmware or software configured to perform thepresent invention may be included in the processors 11 and 21 or storedin the memories 12 and 22 so as to be driven by the processors 11 and21.

The processor 11 of the transmitting device 10 is scheduled from theprocessor 11 or a scheduler connected to the processor 11 and codes andmodulates signals and/or data to be transmitted to the outside. Thecoded and modulated signals and/or data are transmitted to the RF unit13. For example, the processor 11 converts a data stream to betransmitted into K layers through demultiplexing, channel coding,scrambling and modulation. The coded data stream is also referred to asa codeword and is equivalent to a transport block which is a data blockprovided by a MAC layer. One transport block (TB) is coded into onecodeword and each codeword is transmitted to the receiving device in theform of one or more layers. For frequency up-conversion, the RF unit 13may include an oscillator. The RF unit 13 may include Nt (where Nt is apositive integer) transmit antennas.

A signal processing process of the receiving device 20 is the reverse ofthe signal processing process of the transmitting device 10. Under thecontrol of the processor 21, the RF unit 23 of the receiving device 10receives RF signals transmitted by the transmitting device 10. The RFunit 23 may include Nr receive antennas and frequency down-converts eachsignal received through receive antennas into a baseband signal. The RFunit 23 may include an oscillator for frequency down-conversion. Theprocessor 21 decodes and demodulates the radio signals received throughthe receive antennas and restores data that the transmitting device 10wishes to transmit.

The RF units 13 and 23 include one or more antennas. An antenna performsa function of transmitting signals processed by the RF units 13 and 23to the exterior or receiving radio signals from the exterior to transferthe radio signals to the RF units 13 and 23. The antenna may also becalled an antenna port. Each antenna may correspond to one physicalantenna or may be configured by a combination of more than one physicalantenna element. A signal transmitted through each antenna cannot bedecomposed by the receiving device 20. A reference signal (RS)transmitted through an antenna defines the corresponding antenna viewedfrom the receiving device 20 and enables the receiving device 20 toperform channel estimation for the antenna, irrespective of whether achannel is a single RF channel from one physical antenna or a compositechannel from a plurality of physical antenna elements including theantenna. That is, an antenna is defined such that a channel transmittinga symbol on the antenna may be derived from the channel transmittinganother symbol on the same antenna. An RF unit supporting a MIMOfunction of transmitting and receiving data using a plurality ofantennas may be connected to two or more antennas.

In embodiments of the present invention, a UE serves as the transmissiondevice 10 on uplink and as the receiving device 20 on downlink. Inembodiments of the present invention, an eNB serves as the receivingdevice 20 on uplink and as the transmission device 10 on downlink.

The transmitting device and/or the receiving device may be configured asa combination of one or more embodiments of the present invention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the scope of the inventions. Thus, it is intendedthat the present invention covers the modifications and variations ofthis invention provided they come within the scope of the appendedclaims and their equivalents.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a wireless communication devicesuch as a mobile terminal, relay, or base station.

What is claimed is:
 1. A method of controlling interference in a radioresource comprised of a plurality of bands and a plurality of frames,comprising: allocating a dedicated data channel for a specific terminaland a common data channel for a plurality of terminals; and forwardinginformation on the allocated dedicated data channel and the common datachannel to a neighboring base station, wherein the dedicated datachannel is allocated when an amount of data to be transmitted to thespecific terminal, which is waiting in a transmission buffer, is greaterthan a predetermined amount.
 2. The method of claim 1, wherein theinformation on the dedicated data channel comprises the number of thededicated data channel, the number of subchannels contained in eachdedicated data channel, and a resource position of each dedicated datasubchannel.
 3. The method of claim 2, wherein the information on thededicated data channel comprises the number of subchannels contained ina feedback channel or a grant channel linked with each dedicated datachannel and a resource position of each dedicated feedback subchannel.4. The method of claim 3, wherein the number of HARQ (hybrid automaticrequest transmission) processes of the dedicated data channel isdetermined according to a time interval between the dedicated datachannel and the feedback channel or the grant channel linked with thededicated data channel.
 5. The method of claim 3, wherein a transmissioninterval of the dedicated data channel is determined according to a timeinterval between the dedicated data channel and the feedback channel orthe grant channel linked with the dedicated data channel.
 6. The methodof claim 2, wherein a plurality of feedback channels or grant channelsassociated with a plurality of dedicated data channels are multiplexedand allocated to a single subchannel.
 7. The method of claim 1, furthercomprising forwarding, to the neighboring base station, information onan use priority of a plurality of sub-regions contained in the dedicateddata channel, wherein the dedicated data channel is allocated accordingto the use priority.
 8. The method of claim 1, further comprisingreceiving information on a dedicated data channel and a common datachannel allocated for terminals of the neighboring base station from theneighboring base station.
 9. The method of claim 1, wherein thededicated data channel for the specific terminal and the common datachannel for the plurality of the terminals are allocated based oninformation on a dedicated data channel and a common data channelallocated for terminals of the neighboring base station received fromthe neighboring base station.
 10. A base station configured to controlinterference in a radio resource comprised of a plurality of bands and aplurality of frames, comprising: an RF (radio frequency) unit; and aprocessor configured to control the RF unit, the processor configured toallocate a dedicated data channel for a specific terminal and a commondata channel for a plurality of terminals, the processor configured toforward information on the allocated dedicated data channel and thecommon data channel to a neighboring base station, wherein the dedicateddata channel is allocated when an amount of data to be transmitted tothe specific terminal, which is waiting in a transmission buffer, isgreater than a predetermined amount.
 11. The base station of claim 10,wherein the information on the dedicated data channel comprises thenumber of the dedicated data channel, the number of subchannelscontained in each dedicated data channel, and a resource position ofeach dedicated data subchannel.
 12. The base station of claim 11,wherein the information on the dedicated data channel comprises thenumber of subchannels contained in a feedback channel or a grant channellinked with each dedicated data channel and a resource position of eachdedicated feedback subchannel.
 13. The base station of claim 12, whereinthe number of HARQ (hybrid automatic request transmission) processes ofthe dedicated data channel is determined according to a time intervalbetween the dedicated data channel and the feedback channel or the grantchannel linked with the dedicated data channel.
 14. The base station ofclaim 12, wherein a transmission interval of the dedicated data channelis determined according to a time interval between the dedicated datachannel and the feedback channel or the grant channel linked with thededicated data channel.
 15. The base station of claim 11, wherein aplurality of feedback channels or grant channels associated with aplurality of dedicated data channels are multiplexed and allocated to asingle subchannel.
 16. The base station of claim 10, wherein theprocessor is configured to forward, to the neighboring base station,information on an use priority of a plurality of sub-regions containedin the dedicated data channel to the neighboring base station andwherein the dedicated data channel is allocated according to the usepriority.
 17. The base station of claim 10, wherein the processor isconfigured to receive information on a dedicated data channel and acommon data channel allocated for terminals of the neighboring basestation from the neighboring base station.
 18. The base station of claim10, wherein the dedicated data channel for the specific terminal and thecommon data channel for the plurality of the terminals are allocatedbased on information on a dedicated data channel and a common datachannel allocated for terminals of the neighboring base station receivedfrom the neighboring base station.